The full-bodied voice of a Spanish soprano fills the air at a recent talk at the Singapore Conference Hall to mark the building's 50th anniversary.

Its Penang-born architect, Datuk Seri Lim Chong Keat, 85, is giving a lecture on his holistic approach in designing the building, which was gazetted as a national monument in 2010.

He plays the recording by the late Victoria de los Angeles to demonstrate the quality of the auditorium he designed. Now a concert hall, it is mostly used by the Singapore Chinese Orchestra, which has occupied the Singapore Conference Hall in Shenton Way since 2001.

Mr Lim explains how he was influenced by the legendary Bauhaus school of design, where "you cannot design if you are not interested in the entire spectrum of culture".

Trained in architectural acoustics at the Massachusetts Institute of Technology (MIT), he once hosted a dinner at his Pasir Panjang home for de los Angeles after her performance at the Singapore Conference Hall in the 1960s.

But he is far from being only an opera fan.

"Anything that he does, he goes into it in a thorough way. It's inspiring. There's nothing super- ficial about the man," says Mr Tay Kheng Soon. The veteran architect, who was in the audience for the talk, designed the landmark Golden Mile Complex and was one of Mr Lim's first students.

"When he played the music, it was electric. It's not just an architectural space, it's a musical space. That's an example of integrity: a notion of understanding things as a whole."

Returning to Singapore after obtaining his master's degree at MIT, Mr Lim taught for about two years at the School of Building and Architecture, which he helped set up at Singapore Polytechnic.

The school was the precursor to the Department of Architecture at the National University of Singapore.

Mr Lim was also an aspirational model for another former student, veteran architect Tan Cheng Siong, who designed the Pearl Bank Apartments in 1976, known for its unusual horseshoe shape.

He says Mr Lim helped usher in "a brave new world" in the early 1960s, where young architects strove to achieve something worthwhile for soon-to-be independent Singapore.

"We were very young, all that we wanted to know was construction, how buildings are built. He came, tall and young and handsome, very suave and knowledgeable. He spoke the Queen's English, so different from our Singaporean English.

Renaissance man

"He was like an aristocrat, even though he had the crew cut of the US Marines," says Mr Tan. "He created a fantastic impression. He knew about modern architecture, he came with theories of modernism, of Le Corbusier. Singapore wanted very badly to be modern."

Today, Penang-based Mr Lim, who still has close-cropped hair that is more salt than pepper, has an urbane, leonine presence that probably comes from years of commanding attention.

He speaks in accent-free English with a bell-like clarity and closes his eyes during parts of this rare interview, as if focusing on the best way to answer.

He is clearly proud of the Singapore Conference Hall, one of a handful of post-colonial buildings to be designated national monuments. He also designed Jurong Town Hall, another gazetted monument.

After winning a national design competition, he and two partners at his firm at the time, Malayan Architects Co-Partnership, com- pleted the Singapore Conference Hall and Trade Union House, as it was then called, in 1965 at the cost of $4 million. From 1965 to 2000, it served as the headquarters of the National Trades Union Congress (NTUC).

Mr Lim paid attention to diverse aspects of the building, such as its natural ventilation and sun- shading terraces, which made it green before the term gained currency, he says.

Indigenous materials such as merbau and ramin timber were used, as well as a Terengganu basket-weaving pattern that was replicated in its original mosaic tiles.

Some of these features were removed after two rounds of renovation in the late 1980s and around 2001, which included installing air conditioning and removing the interior mosaic tiles. The changes sparked controversy at the time among architects, who felt they irretrievably altered the character of the building.

Mr Lim feels strongly about the renovations made, describing them as a "violation".

He feels that making such significant changes to the building infringed "professional ethics" and that the succeeding architect should have consulted him as the original architect.

Mr Tay, who describes his mentor Mr Lim as a man who does not mince his words, says it should have been a matter of "professional courtesy" when making significant changes to a building but demurs from describing this lack of consultation as unethical.

The architects involved in the renovations declined to be interviewed or could not be traced.

At the heart of this, however, is a bigger debate about conservation in a whirling, changing urban landscape.

Mr Tan, who is trying to conserve Pearl Bank, speaks of a "bad habit" in Singapore, where "charged with productivity and getting things done fast, the value of art, intellectual property, was not respected".

Mr Lim has firm views on any further renovations that might be done to the Hall, or to his other work, Jurong Town Hall.

"Since it is declared a national monument, they should appoint a conservator who should restore as much as possible."

Mr Lim also has an interest in urban planning. As a young man in his 30s, he sat on organisations such as the Housing Board in the 1960s.

He founded the seminal Alpha Gallery in 1971, which exhibited the works of Cultural Medallion recipients such as sculptor Ng Eng Teng and ceramist Iskandar Jalil. He sings arias and plays the viola, piano and harpsichord. He also paints and sculpts.

After retiring in 1995, he became a full-time botanical researcher, maintaining a conservation garden, Balik Pulau, in Penang.

Mr Lim, who describes himself as being on "the cutting edge of botanical research", has published a botanical journal, Folia Malaysiana, for 15 years, and once chaired Malaysia's forestry research institution. A self-taught botanist, he estimates that he has discovered about 40 palms and gingers, his area of specialisation.

In short, in the words of his nephew, prominent plastic surgeon Woffles Wu, Mr Lim is that rare creature, a true polymath, "a Renaissance man".

Dr Wu, who is related to Mr Lim on the maternal side of his family, recalls his uncle's early work, such as a "beautiful modernist house" in the 1970s in Rochalie Drive, which belonged to some family members and has since been torn down.

As a teenager, Dr Wu hung out at his uncle's Pasir Panjang house, where personalities such as pioneering abstract artist Anthony Poon and Richard Buckminster Fuller, an eminent American thinker, inventor and architect, dropped by.

Music soirees were held every month and this "bohemian" lifestyle struck a chord with him.

"I was greatly influenced by him. My grandmother was an opera singer; my grandfather, an amateur painter. Chong Keat was the first guy (I knew) who blended art, architecture, design, style, appreciation of beauty. It was all part of the same creative process," says Dr Wu, who has his own private museum.

Mr Lim says that his "comprehensivist" philosophy, derived from his late friend, Buckminster Fuller, entails an in-depth approach in all his endeavours that is neither "generalist" nor "specialist".

Lauded in Singapore and Malaysia and "comfortable with both", Mr Lim is a global citizen who still travels in his old age. He was awarded Singapore's Public Service Star in 1965 and bestowed the Datuk Seri title in 2002 in Malaysia. This year, he received the Singapore Institute of Architects' Gold Medal, the organisation's highest honour. He received the Malaysian equivalent in 1997.

"Singapore is my fatherland and Malaysia is my motherland," he says, explaining that his doctor father was from Singapore and his housewife mother was from Penang.

Gaining a first in Manchester University for his undergraduate degree before winning a prestigious Commonwealth Fund scholarship to MIT, he sees himself as a "globalist".

"National boundaries don't matter to me. Your first loyalty is to the world," he says.

Mr Lim, who has never married, says only that he is "married to his work".

The youngest of eight siblings, his distinguished family includes doctor and politician Sir Han Hoe Lim, who was the second Malayan Chinese to be knighted after lawyer Sir Song Ong Siang. Mr Lim's elder brother, Mr Lim Chong Eu, who died in 2010, was for 21 years chief minister of Penang.

As a child in a cultured household surrounded by music and books, Mr Lim saw a photograph in a magazine of an iconic house designed by American architectural legend Frank Lloyd Wright in rural Pennsylvania. The house, Fallingwater, was designed by Wright in 1935 and is usually photographed perched on a waterfall.

The image stuck indelibly with the boy, who resolved to be an architect. Years later, while travelling around the United States on the funds afforded by his scholarship, Mr Lim took 3,000 photos of architectural and other sites and visited Fallingwater.

He went one further. Around 1956, during his US travels, he was inspired to track down Wright himself.

He "hitched a ride with some nice ladies in an open Cadillac" to Taliesin, Wright's estate in Wisconsin. Mr Lim, then an architecture student in his 20s, witnessed segregation, where whites entered the front of the bus and "coloureds" the back. ("I used to decide to sit in the middle".) But he remembers it mostly as an extraordinarily "open-hearted" time in America, where doors were often not locked and famous people not cocooned by minders.

At first encountering the students and apprentices who lived at Taliesin then, he was, eventually, incredibly, granted an audience with "the great, wise man" himself.

"There was no inquisition, no 'who the hell are you?' He asked me, 'What can I do for you, my boy?'" Mr Lim says.

They talked about Wright's "organic architecture" and his revolutionary Guggenheim Museum for about half an hour. He says that Wright might have granted him an audience because he was courteous and "never a groupie". He did not even take a photo to commemorate the event.

Disdainful of the "groupie" Wright students he had met at Taliesin, he eschews derivative gimmicks and fashions as an architect.

Detractors called him a bare- faced liar when he told them he had seen Wright, by then an old man who died a few years later. ("I wanted to meet him before he conked off," Mr Lim says.)

A man who walks to his own drumbeat, he has learnt not to let criticism get him down.

He smiles when he recalls how critics slammed his lack of academic credentials as a botanist. His friend, world-famous palm specialist and botanist John Dransfield, with whom he has done joint research, told him: "What is better than having a PhD is not needing one."